Home/BlogThere is an aspect of weather generation and storminess that I never see discussed, and which I think could be important to understand when discussing possible changes in weather with climate change.
It has long been known that the atmosphere is a very inefficient heat engine. The rate of kinetic energy generation supporting the atmospheric circulation is only about 1% of the rate of solar heating (e.g. Peixoto J P and Oort A H 1992 Physics of Climate). Since most of what we perceive as weather is related to wind, one way or another, we can roughly say that only 1% of the solar energy absorbed by the Earth goes into the creation of weather systems.
I suspect that when we see periods of greater or lesser storminess on a global basis, we are seeing fluctuations in this efficiency. If air mass temperature differences build up over a period of days or weeks, say with cold winter air masses over N. America or Asia intensifying in the winter, the temperature contrast (available energy) for the creation of storms increases. (I would imagine that storminess was considerably more energetic during the ice age(s)…I’m sure someone has researched this issue before.)
Since it takes time for low pressure systems to form and draw upon this potential energy from the temperature contrast between air masses, there is a time lag involved in the cycles of storminess. The potential energy built up is released as low pressure areas form and their circulations cause warm air to rise up and flow over the cold air masses, and the cold air slides under and displaces the warm air masses.
Global warming theory has traditionally expected that the equator-to-pole gradient in temperature would be reduced during warming. Observations suggest this has indeed occurred, at least over the Northern Hemisphere. So, the energy available for storm formation has decreased. I suspect the effect is small, though. (Storminess is also related to the tropospheric vertical temperature lapse rate…a steeper lapse rate can support more kinetic energy generation).
[By the way, I don’t think the decrease in the equator-to-pole temperature contrast is a fingerprint of human-induced warming…it’s a reflection of the geographic distribution of land, which will warm faster than the ocean no matter the cause of the warming.]
What is interesting about the 1% efficiency is how small that number is, which is related to the fact that weather is driven by relatively small temperature contrasts over relatively large distances: a few degrees over hundreds or thousands of kilometers. In a car engine, which can also be considered a heat engine with about 25% efficiency, the mechanical work that is done is drawing on temperature differences of hundreds of degrees over a few inches.
If the atmospheric heat engine efficiency were to increase from an average of 1% to 2%, that would be a doubling of the kinetic energy involved in weather systems…yet the thermodynamic efficiency would still be very low.
What does all of this have to do with global warming? I don’t know…I just think it’s interesting.
Yes, very interesting.
Heh – your title reminded me of a claim from Kerry Emanuel in his book Divine Wind. (All in all, it’s a decent book on tropical storms considering the author’s view on CAGW.)
Tropical storms, of course, feed off the latent heat in warm moist air at the ocean surface and dump waste heat in the cold air aloft so are not so affected by polar amplification or whatever people want to call that.
He claims:
“… it turns out a hurricane is an almost perfect example of a Carnot heat engine.”
“There is one other effect on the energy of hurricanes. The terrific winds blowing across the surface near the eyewall are constantly being dissipated by friction.”
“In a mature hurricane, almost all of the frictional dissipation occurs in the inflow layer. Thus the power of the winds is converted back into heat, which then flows back into the system at the high temperature reservoir where heat is being injected in the first place. This recycling of waste heat makes hurricanes somewhat more powerful than they would be otherwise.”
“The hurricane Carnot heat engine, with its recycling of waste heat, is one of the more efficient natural generators of power on earth.”
I suppose, though the main work most hurricanes do is send their energy out as ocean swells and moist air to rain out as the storm dissipates. I tend to look at storms as energy concentrators, with the peak concentration showing up inside lightning bolts. All this talk about efficiency makes me think there should be a percentage of theoretical output attached to it.
http://en.wikipedia.org/wiki/Tropical_cyclone#Secondary_circulation:_A_Carnot_heat_engine
ftp://texmex.mit.edu/pub/emanuel/PAPERS/Physics_Today_2006.pdf‎
yes, weather systems are examples of “dissipational structures”…they have positive feedback processes which can temporarily concentrate energy, but in the end they dissipate the potential energy they grew from. Tornadoes are another good example.
I’ve long found the term “Dissipative ‘Structures'” annoyingly inaccurate.
Trailers in a trailer park are “structures,” not just because of their order, but of their permanence, at least until a tornado blows through. But the tornado that destroys them? …a “structure?”
No. Because of their destructive power and lack of permanence (thankfully), “Dissipative Anti-Structures” would seem a much more appropriate term. Unfortunately it’s way too late to change it now.
Efficiency is irrelevant. A piston engine is causing a tiny effect globally with its steep temperature gradient, and its energy output is trivial. A tropical cyclone has far larger effects, because the minor gradients involved are over large masses and distances. It can “efficiently” rearrange a city, e.g.
Horses for courses.
Roy, you write “Since most of what we perceive as weather is related to wind”
If Anastassia Makereiva is right about why winds blow at all, it would not be surprising if this were found to be another reason why climate models don’t seem to emulate the real world very well.
That heat engine has everything to do with climate change since it provides the negative system response that occurs whenever any forcing element tries to divert system energy content away from that set by mass, gravity and insolation.
It is an aspect that have been drawing attention to for years and the main physical manifestation of it is latitudinally shifting climate zones.
This recent article is highly relevant:
http://www.newclimatemodel.com/the-gas-constant-as-the-global-thermostat/
The fact that little energy is dissipated moving the atmosphere is not evidence of inefficiency. On the contrary, it means that little energy is required to initiate and maintain the massive motions that comprise the weather systems, and consequently that the convective atmosphere is a superefficient engine for transporting heat to where it can be most efficiently radiated to space.
Interesting.
Global warming is a thermodynamic transformation, or engine. Heat is transferred from the upper atmosphere, which is presently cooling, to the warmer surface, which is warming. Work is required to transfer heat from the colder atmosphere to the surface. The work is available: it is that of gravity in the form of reduction of stratospheric geoptential heights, which are decreasing.
I’ve always liked thunderstorms, so I’ve paid attention to them. I watch them coming on the radar, and then watch the lightning on the deck if it’s after dark.
It seems they are just not the same as they were decades ago. It’s not that we never have any powerful storms, but the fronts are less organized. Twenty years ago, the storms would arrive in broad fast-moving fronts. Now we seem to get slow moving scattered storms.
I tend to think it is because the air in the Arctic just isn’t as cold and dense. The Arctic has really warmed up.
Arctic ice extent near to 2003 level on 4th November……
Arctic ice extent is a poor proxy for temperature because the ice can be broad but thin due to wind or ocean currents.
Why use a proxy when we have the data? The link Dr. Spencer provides has the data. And whereas the average global anomaly has been 0.17 since 2000, for the Arctic it has been 0.58.
Except that the real surface data from the arctic revelas that the permanent ice pack (multi-year ice) is GROWING in volume (surface area and thickness) and has been for several years.
Err – No it hasn’t….
Unless your idea of “growing is the following…
http://www.epa.gov/climatechange/science/indicators/snow-ice/sea-ice.html
We have it all nicely understood, just a matter of a few simple engineering principles, well-known ideas such as heat engines. What clever fellows we are, understanding these things in such nice simple terms. That’s why we are so good at making climate models, which are very accurate and reliable predictors of the future climate. Simple, really, when you think about it in basic practical engineering terms. No need to put on our thinking caps. What’s all the fuss about? No need to develop new understanding to account for climate change. The science is settled. The great thing is how cheap, efficient, and reliable are our climate models, and how much good they will do us all as the years advance. Again I say, what clever fellows we are. Carping clowns such as Makarieva et al. http://rspa.royalsocietypublishing.org/content/467/2125/1.full.pdf should just shut up and stop suggesting that some thought is necessary about the weather process. As I just said, the science is settled; they shouldn’t hint that it might not be settled, or make unsettling suggestions that new ideas might be helpful.
We know nothing about how the atmospheric heat transfer works, the science is not settled, we got millions of questions, we know only one thing for sure: CO2 does not cause global warming and all of those who think emissions control might be important are lunatic, right?
Surely we can take that as a /sarc Christopher ??
Think Mag took you verbatim.
wayne: This blog and its community seem very determined that climate change is cyclic and natural, and that AGW is not a problem. Now some confess here that the science is not settled and we got millions of questions. I just wonder how you all are so confident that emissions control is a madness.
Dr. Spencer,
I don’t know why you bring “global warming” into this great topic. Now if you were to more ask what is the difference in the weather systems between warm periods globally and cooler periods globally it may be more palatable.
I agree, this is a very interesting topic and wind is the primary mover. Temperature at its base is the ratio of pressure to density. Temperature varies directly with pressure but varies inversely with density. So just saying there is a temperature difference doesn’t seem to really tell the whole story or maybe I’m looking a layer too deep.
I’m just now trying to learn a bit more on meteorology in the last year and I tend to attempt to make sense of all of the aspects without getting too deep in the maths until later, maybe that is unavoidable. Am I wrong in viewing that in a pressure systems, lets say a 1020mb up against a 990mb, the pressure more drives the horizontal gradients and the densities (you can convert the ratios to temperature or vice versa) more dictates whether a warm air mass is going to ride up over the cold air or whether the cold air mass is going to ride up over the warmer air (rarer), an inverted system. And then humidity also plays hugely into this relationship and it’s so easy to get confused.
Then you also have the curl and convergence into a low pressure area usually and that cannot be ignored either. It’s so easy to oversimplify this subject and is why meteorologists have my respect usually until they start to carry a political tone.
So when you say temperature difference I tend to then ask, ok, at what pressure is this temperature. Is that wrong?
Sorry, in my speed and efficiency I linked to a response to the Makarieva et al. paper. The paper itself is at http://rspa.royalsocietypublishing.org/content/466/2119/1893.full.pdf . Never mind, the science is settled anyway.
Settled, you say? Science is NEVER “settled”. There is always more to learn.
The heat engine is not dissipative.
The amount of kinetic energy exchanged between surface and atmosphere during adiabatic ascent and descent remains constant as long as mass, gravity and top of atmosphere insolation stay the same.
If anything else changes then only the amount of gravitational potential energy in the atmosphere can change otherwise surface temperature would become too high or too low for the surface temperature to both maintain atmospheric suspension off the surface and retain top of atmosphere radiative balance.
That would be the true breach of the S-B constant.
Once one deducts the portion of surface temperature (kinetic energy) required to keep the weight of an atmosphere off the ground then surface temperature is what is predicted by the S-B constant.
Changes in the speed or size of the heat engine as a result of anything other than mass , gravity and insolation simply alter the amount of gravitational potential energy relative to the amount of kinetic energy.
Read my article and apply thought:
http://www.newclimatemodel.com/the-gas-constant-as-the-global-thermostat/
In convective systems, most of the ascent is not adiabatic. Is called “pseudo-adiabatic” because the condensation of moisture releases additional heat. The available convective energy is a direct result of this condensation – without it the atmosphere would be stable.
The water cycle is a separate issue.
The phase changes of water simply make it easier for the non-water based part of the adiabatic cycle to keep the system stable.
Even without the water cycle (or any GHGs at all)uneven surface heating produces density variations that produce convection and prevent an isothermal atmosphere.
Of course, individual weather systems can be ‘dissipative’ of kinetic energy locally and regionally by pushing upward and converting KE to PE
but
for every such uplift there is a corresponding descent in a higher pressure cell elsewhere which converts PE back to KE so for the system as a whole there is no dissipation.
It all comes back to the adiabatic and diabatic energy ‘loops’ that I described some time ago elsewhere.
Warmer air can hold more water and holds more energy is a common saying, so that’s why we should have more violent weather in a warmer world.
Would anyone then explain why the Antarctica and the southern ocean have so violent storms?
And also tell why the worst storms in the northern part of the world is not in the summer but more in fall and winter.
“Would anyone then explain why the Antarctica and the southern ocean have so violent storms?”
Its about the polar vortices. Where the pressure lines are a-closin’, that where the winds are a-blowin’. See if you can spot the Drake Passage.
http://weather.unisys.com/upper_air/ua_hem.php?plot=s5&inv=1&t=cur
Wanna join Greenpeace?
http://www.youtube.com/watch?v=Jld5pIUKhCE‎
I said above:
“Changes in the speed or size of the heat engine as a result of anything other than mass , gravity and insolation simply alter the amount of gravitational potential energy relative to the amount of kinetic energy.”
but should have added that changes in the balance between KE and PE are then negated by circulation changes which we perceive as climate change.
So GHGs will change climate zone distribution but since the greenhouse effect is all a product of atmospheric mass our influence would be too small to measure.
Stephen, sorry, this does get rather old.
I would be flat amazed if even one person understands exactly what you are saying in entirety. You seem a source of a non-stop flow of words including PE, KE, gravity, mass, pressure and your adiabatic loops and those are all science terms but but don’t you understand no one follows your chain of logic? It is full of flaws. This has been gone over umpteen times but you never seem to ‘get it’. I thought Phil. just might have some success recently but it appears, no.
Sorry to bring you back to the real science. If you can’t in the end put it in math and equations (science’s language) all of the words are meaningless and if you would actually do the math you would find your own mistakes. Sigh. It’s not that sometimes you say correct statements, you do, but you can’t then take those and intermix them with other totally incorrect thoughts and statements or you just get mush.
I’ve waited a year before saying that not wanting to hurt your feelings.
wayne.
I must respectfully disagree.
There are others who have got the message from words alone.
The maths is truly very simple.
The surface to atmosphere energy exchange is net zero whilst the top of atmosphere radiative balance is also net zero but in each case there are variations about the mean.
The point is that one can see from the Gas Laws that the two sets of energy exchange juggle atmospheric PE and KE so as to adjust overall circulation which alters the rate of non-radiative energy throughput to maintain system balance despite any forcing elements other than mass, gravity or insolation.
I have read your words and numbers but think you have lost the true simplicity of the system in a mass of irrelevant detail about the many different types of energy exchange that go on within an atmosphere.
Only the surface to atmosphere net exchange and the top of atmosphere net exchange matter and both net out to zero.
There really is no more maths required.
Phil tied himself in knots by ultimately refusing to concede that the kinetic energy needed to lift mass off a surface is what determines the height of an atmosphere and therefore the volume of that atmosphere.
I agree though that many are just unable to follow the logic simple though it be.
Huh ?
I’m with Wayne here. After the first 20 or so times of reading Mr. Wilde’s posts, I realized that they are really just endless random permutations of the same non-rigorous statements. His “papers” are no better.
Stephen, you should have gone into law, because you can most certainly convince a jury with words. But you can’t convince scientists without equations and quantitative reasoning. You have neither. But the bigger problem is you don’t understand why having neither is a problem at all.
Random ?
If only you knew how much work I have put in for more than 60 years to achieve internal consistency.
I was deeply involved in the study and observation of weather and climate for decades longer than Hanson et al.
To me, you and they are mere newbies 🙂
Note too that juries are supposed to arrive at the right answer aren’t they ?
And I don’t do ‘papers’.
I do essays comprised of logical reasoning.
“The point is that one can see from the Gas Laws that the two sets of energy exchange juggle atmospheric PE and KE so as to adjust overall circulation which alters the rate of non-radiative energy throughput to maintain system balance despite any forcing elements other than mass, gravity or insolation.”
Stephen, sorry, I should have made that comment a more personal email exchange. You may not realize I have spent literally many hours on your thoughts, trying to make them more formalized, in maths, and I do see, or I think I see, your thoughts on those three aspects, the atmosphere’s mass, planets gravity (from its mass), and insolation (albedo already removed) being close to correct over very long time periods.
But you seem to be jumping in your thoughts from one scale to another scale without explanation between the two. Are we speaking of monthly or shorter scales (weather) or multi-decadal scales (climate) and scales do matter greatly. So many times your words imply we are speaking of weather.
As to net energy at the surface and TOA being both net zero, you lose me there. At short scales that is not correct or Dr. Spencer’s AMSU charts would not have the jiggles and longer term secular differences and the short-term temperatures would not change. In fact that non net-zero aspect is what AGWers are claiming, because between the 1970’s and 2000 the temperature globally averaged did rise a half a degree. They say it was co2, both you and I say no but you can’t say KE and PE always exactly equalizes the net energies over long times so really the temperature records are wrong and the GASTA should be a straight line.
Higher surface temperatures will raise the atmosphere (PE) but that is but a fraction of what happens thermodynamically, that is the Cv-Cp portion because some work was performed on the atmosphere but that in itself does not then cool making the net temperature change zero.
See where many are having a problem following you? Specify the scales and explain when you jump from one to the other and exactly why.
Now you thoughts on the jet stream altering between meridional and zonal over climate scales, much better thoughts, and because of you I have been watching that area over the last few years, seems you may very well have something there! No equations necessary.
“As to net energy at the surface and TOA being both net zero, you lose me there.”
People who are good with numbers often have problems with words and vice versa.
It is the energy EXCHANGE between surface and atmosphere that nets out to zero and the energy EXCHANGE between atmosphere and space that nets out to zero.
Time scales do not matter because whatever forces seek to disturb the basic equilibrium are always negated after a while by circulation changes.
I also acknowledged that there are variations either side of the mean all the time but those variations are simply lag times between disruptive forcing elements and the negative system response.
Anyway, no point in going too deeply into more words because some really do have problems seeing how simply it all fits together.
As far as I can tell nothing that I am suggesting is much different from what was once the standard understanding of the gas laws extended to an atmosphere around a sphere rather than a parcel of air within an atmosphere.
You really do not need to quantify every thermodynamic event within an atmosphere when it all has to net out to zero if an atmosphere is to be retained.
ANY long term imbalance will result in a surface temperature too high or too low for the S-B constant to be observed AFTER deducting the kinetic energy required to hold the weight of the atmosphere off the surface at a height determined by mass, gravity and insolation.
The radiative theory simply does not take account of the fact that the ‘surplus’ heat at the surface is all used in supporting the weight of atmospheric mass.
If radiative molecules acquire more energy than is required to support their mass they simply rise higher and cool until radiation up from them equals radiation down from them for a net zero effect on surface temperature and energy throughput.
I accept that some cannot sort out these concepts from words alone in which case I can only suggest more detailed consideration of the Gas Laws.
It is those circulation changes that manifest themselves in shifting jets and climate zones. As you say, no equations needed to realise that.
What does rotation of earth hv to do with wind? Suppose earth spun twice as fast, more wind or less ?
Rotation is he primary cause that prevents eficient heat flow from tropics to poles, and thus causing large temperature gradient and – winds. I the earth weren,t rotatin, the Dt between eq and poles would be less than 10c in free troposphere,more like 5c. Larger at the surface of course, like 15 c, but compare it to 40~50 c we have now.
Hmm is that why Venus temperature at the poles is the as at the equator
Well, obviously, but there are other factors to consider. I got the whole idea from a paper by farrel (1990) where he says that speed of heat transfer is about same order of magnitude as external buoyancy waves at tropopause, afaik on order of 100m/s, and the atmospheric column as a whole, considering its temperature and heat capacity cools at about 2-3 k/day. 10000 km divide by 0.1 km/s gives 1e5 sec or 1.5 days, yielding 3-5 k difference. Now on venus obviously heat capaciy is hundred tîmes higher but also atmospheric lapse rate s different too plus mysterious superrotation screwes everything… afaik in upper atmosphere the diffrence is higher there compared to the surface, kinda opposite to the earth situation.
coturnix, do you have thoughts about why the atmosphere has a kinky temperature profile? (Nocturnal inversion, tropopause, stratopause, mesopause.) Can that also be related to the rotation of the earth? How? I suppose the rotation of the earth has two aspects, one to do with cyclic variation of the temperature of the surroundings (sun and outer space) to which any one place is exposed, and the other to do with conservation of angular momentum of air? Each might have an effect on the temperature profile? What is the topology of the profile overall?
Roy-On vertical temperature gradients playing a role, too: I think it would be more accurate to say that the vertical temperature gradient is more important in the tropics, where there is only slight marginal temperature change with latitude compared to outside the tropics.
You know I think what causes the equator to pole temperature difference to be what it is in the first place is probably worth understanding and talking about. It’s not just that the tropics receive more solar energy than the poles-if that were the case the the difference would be a *lot* larger than it is. The Earth system may not be very good at turning heat into mechanical work but it does transport a lot of heat from the equator to the poles.
Ionization stratosphere by cosmic rays affect the block circulation. This data with a minimum of 2009.
http://www.wrmiss.org/workshops/seventeenth/Matthiae.pdf
An Arctic front will drop south through the Prairies on Sunday then continue southeast and reach southeastern Canada by Tuesday next week.
Temperatures behind this front will be well below normal. Strong energy aloft will dive toward the Ohio Valley Tuesday and Wednesday and depending on the speed of this energy we may see a surface storm developing over the eastern U.S.. With fresh, cold air coming in, there could be a swath of accumulating snow northwest of the surface storm over the interior NE U.S. and possibly into extreme southern Ontario Wed/Thur as the storm eventually strengthens off the U.S. Northeast Coast and turns into a major storm for parts of Atlantic Canada by Thursday.
.
Not all of the models are on board with this idea though, as some are much more progressive and just have the cold air overwhelming Southeast Canada and the Northeast U.S. and surpressing any storm development farther to the south and keeping it weak.
We should have a better idea on the evolution of all this by Friday/Saturday. We are still in the wait and see period with this. I will certainly keep you posted.
http://www.cpc.ncep.noaa.gov/products/stratosphere/strat_a_f/gif_files/gfs_t30_nh_f120.gif
http://www.accuweather.com/en/weather-news/arctic-blast-takes-aim-at-cent/19726711
Dr Spencer writes above: “There is an aspect of weather generation and storminess that I never see discussed, … It has long been known that the atmosphere is a very inefficient heat engine.” Come on, Dr Spencer, give us a bit more precision of discourse than this! Surely if they are so “inefficient”, that tells you that the model as a “heat engine” is not a suitable one?
It is nonsense to speak of the weather system as a heat engine. A heat engine predictably and reliably converts energy from a hot reservoir into work, and discharges waste energy to a cold reservoir. Work, roughly speaking, is registered as the lifting of a weight that can be accessed for further energy uses.
True, windmills could count as heat engines in that sense, being driven by solar radiation and discharging waste by radiation to outer space. But at present windmills are not weather. I don’t think they are the topic of interest here?
Perhaps a more nearly appropriate model would be as a sort of heat pump? Moving energy from the ground to the upper troposphere faster than would occur under some reference condition, or somesuch? Not against a temperature difference, but still faster than what would happen otherwise. Otherwise? What would be the reference condition? Perhaps one might ask by how much does convection dominate the energy transfer within the atmosphere, so much that radiative transport within the atmosphere looks feeble beside it? Perhaps the reference condition could be ‘”frozen” convection, virtual radiative transfer only’?
Radiative transfer of course is the only game in town when it comes to transfer direct from the land-sea surface to space, and from the atmosphere to space.
For transfer from land-sea surface to atmosphere, radiative is small-fry compared with non-radiative (conduction-evaporation-convection). Small-fry, but not to be forgotten or denied.
Christopher Game: “It is nonsense to speak of the weather system as a heat engine.”
Everything in Nature is a heat engine. You and I are heat engines, everything that moves, moves because there is some sort of natural heat engine behind. In particular, the winds and the ocean currents move because a heat engine embedded in nature propels them. Even gravity, if we are to believe Verlinde, may be a heat engine.
A heat engine is one of the manifestations of the second principle of thermodynamics: heat flows from higher to lower temperature regions and performs mechanical work in the process.
“What does all of this have to do with global warming? I don’t know…I just think it’s interesting.”
Roy, it means less extratropical storminess.
“According to any textbook on dynamic meteorology, one may reasonably conclude that in a warmer world, extratropical storminess and weather variability will decrease. The reasoning is as follows. Judging by historical climate
change, changes are greater in high latitudes than in the tropics. Thus in a warmer world, we would expect the temperature difference between high and low latitudes to diminish. However, it is precisely this difference that gives rise to extratropical large-scale weather disturbances. Moreover, when a winter day in Boston is unusually warm, the wind is blowing from the south. Similarly, when the day is unusually cold, the wind is generally blowing from the north. The possible extent of these extremes is determined by how warm low latitudes
are and how cold high latitudes are. Given that we expect high latitudes to warm much more than low latitudes in a warmer climate, the difference is expected to diminish, leading to less variance.”
“Nevertheless, advocates and the media tell us that exactly the opposite is the case… Clearly more storms and greater extremes are regarded as more alarming than not. Thus the opposite of our current understanding is invoked in order to
promote public concern.”
(Lindzen, 2005)
Dr. Spencer, I think heat engine is a pretty good term if I am understanding you correctly, a horizontal one at that.
These large air mass systems do start slowly and over time pick up speed, every 1000 meters in thickness of these large air masses have a mass of about a metric ton per square meter. We just had some days of 36 km/hr wind (≈23 mi/hr) and over many states just imagine that energy on the move! At some point it has to either stop, slowly dissipate or change direction and I wonder just how much of that energy dissipates as just simple surface friction along the way.
In climate-talk we are so used to speaking of 240 W/m² or such feeble amounts of radiative energy transfer but at 36 km/hr and 2000 meters thick that air holds 1/2·2000 kg/m²·(10 m/s)² or 100,000 J/m² column of static kinetic energy and that much can travel for a thousand miles. Whew! Now every second that mass moves 10 meters at that velocity so the flux rate passing by is even greater, 1,000,000 W/m², that is if the air mass is two kilometers thick at that speed, scale accordingly. Puts that into perspective what the little ol’ wind can do to equalize our temperatures.
wayne, you are so close to seeing my point about the power of circulation changes within a contracted or expanded atmosphere to regulate system temperature.
Note that the vertical column is not just static kinetic energy (heat), it also contains a substantial amount of potential energy (not heat).
Every time air rises or falls relative to the surface it converts KE to PE or PE to KE.
Air is always rising or falling relative to the surface even when appearing to be in a horizontal flow.
On average at any given moment 50% of the atmosphere is rising and 50% falling.
Roy,
It might be worth noting that most of the kinetic energy invested in a cubic meter of air involves motions near the speed of sound not the velocity of its center of mass. Take the energy released by cooling that volume 1 degree and compare that with the change in wind velocity required to release the same number of joules.
Cooling air by transfer to cooler temperatures, i.e. thermal dissipation, is a far more efficient energy dissipation mechanism than viscous dissipation through macroscopic motion, i.e. Navier-Stokes.
pdq
Convection is not always needed for clouds to form stable air can form clouds also .I notice this as the temperature falls as it is doing now and there is low level cloudiness early in the morning.
http://eesc.columbia.edu/courses/ees/climate/lectures/atm_phys.html
One effect of this convection at the equator has nothing to do with how much energy is required to drive it or how much heat is moved by it. This effect is clouds and it is a negative feedback on the convective process in that it limits the heat impinging on the ocean – the heat that drives the process. So, it results in a cooler surface than otherwise. This heat can’t show up somewhere else other than outer space.
Hey Dr S., what’s up with this month’s global temps?!
“And also tell why the worst storms in the northern part of the world is not in the summer but more in fall and winter”
The potential meridional temp gradient(warm south/cold north) grows mostly in response to high latitude cooling.
Along the equator or lower latitudes, what would be the maximum temperatures that represent what that region is contributing to the warm side?
In the higher latitudes, what would be the minimum temperatures from that region?
In the south, seasonal variations might contribute to a 20 C/36 F degree variation(much less in the tropics). In the Arctic, that variation is 3 times greater, let’s use +70 F to -50 F and a difference of 120 F. Clearly then, when temps are close to the coldest at both places is when the gradient is greatest.
There is a lag in the atmospheres response to changes in solar insulation(warming well after the sun angle has peaked in Summer and cooling well after the sun starts heading north again in Winter).
This makes climatological Winter(coldest temps) a month later than the calendar.
In late Winter, the south is warming from the increasing sun angle, while the far north has yet to see the sun rise. This often leads to the greatest disparity over the shortest distances as we head into early/med Spring and we see violent weather peak.
One reason for early/mid Spring to be the peak for violent weather, even as high latitude temps have already started warming is that the temp gradient moves farther north where the Coriolis force(from the earths rotation) increases greatly vs what was available farther south in the Winter.
There is also, at the very least an equal if not greater amount of heat and energy being transported by ocean currents. Maybe not as efficient as the atmosphere(I’m surprised at the 1% number from Dr. Spencer and would think temps in the Arctic would be much colder if it were so low) but the mass involved with water vs water vapor transport is several orders of magnitude greater.
No piling on please; I am a non scientist observer.
If the Atlantic hurricane season is inactive, then is it a correct assumption that the Gulf Stream will carry/deliver more heat energy to the far North Atlantic (eg Arctic region, NW Europe, Scandinavia) than when the season is more active. Do hurricanes by their nature have the effect of moving the ocean heat energy to the atmosphere in the lower latitudes, and by their absence, the heat energy is available to be transported to the north where it is there exchanged with the atmosphere?
“This makes climatological Winter(coldest temps) a month later than the calendar”
Should have stated that climatological Winter(coldest 3 months) are shifted a month later than the 3 months with the least amount of solar energy………Nov/Dec/Jan have the weakest sun but coldest temps are Dec/Jan/Feb.
Or, the shortest day of the year is around Dec 21st but the climatological bottom in temps is around a month later.
Another interesting feature of the atmosphere is wind. I became interested in the question of how much wind energy is being taken out of the atmosphere by the deployment of wind turbines. It’s a simple calculation once you know the parameters:
— the total wind power produced from currently deployed wind turbines
— the efficiency of conversion of wind to kinetic energy (I consulted the Betz theory of windmills http://en.wikipedia.org/wiki/Betz%27_law )
— the average wind speed as a function of altitude and latitude (I referred to my old copy of Walter Munk’s book “Rotation of the Earth”)
— density as a function of altitude
I got the surprising result that the wind turbines deployed today are extracting several tenths of a percent of the wind energy available up to the tropopause. Presumably this will increase substantially in the future.
I have no idea what this means for climate, if anything.
Roy Spencer says “(I would imagine that storminess was considerably more energetic during the ice age(s)…I’m sure someone has researched this issue before.)”
Apparently ‘yes’ to both.
1%, OR 2%?
M.V.Kurgansky arrives at the figure of 1% in 2 different ways. “According to the above data, ε = 1%. This is consistent with the estimate of the atmospheric heat engine efficiency derived earlier by means of the power arguments”
Maocang Tang and Meidong Guo put it currently at 2%, by adding effects of both positive and negative atmospheric heat engines, in their discussion of Great Ice Age Cycles. “It is about 2% at present and depends on different geological periods, mainly dominated by variation of efficiency of ‘positive heat engine’ for it’s counterpart is passive.”
(found by Google search on the term, in quotes, “ATMOSPHERIC HEAT ENGINE EFFICIENCY”)
And that’s as far as I could get. I can’t afford the publications, and haven’t done the math involved in a few decades.
Christopher Game says:
November 7, 2013 at 1:22 AM
…
It is nonsense to speak of the weather system as a heat engine…
On the contrary, the weather system is by definition a thermodynamic heat engine, producing thermodynamic work (i.e. wind – mainly) from temperature differences.
When work is produced from temperature differences, there is an absolute limit – by the 2nd Law of Thermodynamics – to the efficiency that can be obtained. Here, efficiency is defined as the ratio of the work obtained to the thermal energy from the higher temperature source. The remainder of this thermal energy is rejected to the lower temperature sink.
This theoretical efficiency limit is known as the Carnot efficiency, and can be expressed in terms of absolute temperatures as:
Ec = (T_hi – T_low) / T_hi
So if your high temperature is 300K (27C) and your low temperature is 275K (2C), this efficiency limit is:
Ec = (300-275)/300 = 25/300 = 0.0833, or 8.33%
Now, it is impossible to reach this limit, if only because a single Carnot cycle would take infinite time. It is not practically possible even to come close. I am not familiar with any engineered systems that even reach half of the Carnot efficiency. So I am not surprised that the thermodynamic efficiency of natural weather systems as work-producing heat engines is around 1%.
I have long noted the disconnect (as Lindzen and others have) between mainstream greenhouse theory predicting reduced temperature differences, both vertically due to the moist adiabat (e.g. the “tropical hot spot”) and horizontally due to the higher sensitivity of polar regions (less water vapor in colder regions means additions of CO2 have more effect, and snow/ice albedo amplification), and the headline predictions of more severe weather. Basic thermodynamic analysis would indicate that these reduced temperature differences should decrease the thermodynamic efficiency and lead to less severe weather.
Is it just the wind? I would have thought ocean currents were also propelled by temperature differences between the equatorial and circumpolar oceans. There is also another mechanism involved, the tidal pumping by the Moon. As angular momentum is lost, converted to heat, the Moon recedes.
This 1% efficiency, is it averaged over some number of years, or a daily snapshot? It seems to me that the earth atmospheric system, and the ocean as well, work in bursts. They accumulate energy, then release it in bursts like, say, the 1998 super-El-Nino or a major hurricane season. Then the system deflates for a number of years.
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